Electric starting system for small engines



(3 United States Patent nu 3,536,051

[72] Inventor LyleJ-Hamman 2,689,310 9/1954 Kaufmann 290/38 Eaton Rapids, Michigan 3,084,561 4/1963 Mattson 74/6 [21] Appl. No. 712,169 3,219,021 11/1965 Mercer et al. l23/179(P) [22] Filed March 11, 1968 3,227,236 1/1966 Burton 74/6 [45] Patented Oct. 27, 1970 3,237,079 2/ 1966 Mas 321/8 [73] Assignee Eaton Stamping Company 3,331,363 7/1967 Holton 123/179(G) Eaton Rapids, 2,655,047 10/1953 Smith 123/179(O) a corponuon Michigan Primary Examiner-Wendell E. Burns Attorney-Beaman and Beaman [54] ELECTRIC STARTING SYSTEM FOR SMALL ENGINES ABSTRACT: The invention pertains to an electric starting 14 mums 9 Drawmg Figs system for small internal combustion engines of the type em- [52] 11.8. C1. 123/179, ployed with lawn mowers, garden tools and small tractors, The 74/6, /5 321/8 system includes an electric starter consisting of an electric [51] 1!". C1. F02]! 11/01 motor driving a starter gear which engages gear teeth formed 1 [50] Field of Search ..l23/l79(C( 3 on the engine flywheel, the electric motor being energized E 179(0), 1790 from a small compact battery of the rechargeable type within 2 /36, 26 a battery casing which includes an electric switch and a key E lock for operating the switch. Mounting means are formed 1 [56] References cued upon the electric starter and battery casing, and output and 1 UNITED TAT PA E recharging connections are defined on the battery casing 5 1,504,392 8/1924 Strauss l23/l79M r y h battery m y be connected to the electric motor. 290/50 1 and readily connected to recharging apparatus.

2,506,780 5/1950 De Salardi l l 4 r l 1 Pateliteafdc .27,1970: 3,536,051

Sheet 1 of5 LYLE J HAMMAN ATTORNEYS INVENTOR Patented 27, 1970 Sheet Qzmm INVENTOR LYLE J. HAMMAN ATTO R NEYS Patented fOa. 27, 1970 v 3,536,051

Sheet fly of5 INVENTOR LYLE J. HAMMAN 'I Mamm ATTORNEYS ELECTRIC STARTING SYSTEM FOR SMALL ENGINE BACKGROUND OF THE INVENTION The invention pertains to the field of art including self-contained electric starter systems for small internal combustion engines wherein the system includes a portablepower source, such as a battery, for the energization of an electric motor which drives the engine flywheel for starting purposes.

With the increasingly widespread use of small internal combustion engines in lawn mowers garden tillers, snow'blowers, lawn sweepers, go carts, small lawn tractors, etc., the need for easily operated starters for such engines has increased. While a new small internal combustion engine having a manually operated starter, such as of the recoil type, may be relatively easy to start, the accumulation of deposits in the combustion chamber, on the spark plug, upon the exhaust ports, and within the carburetor, as wellas a lowering of'the fuel compression and deteriorating of the ignition system, makes the starting of the engine increasingly difficult as usage continues. Small engines have a reputation for becoming temperamental" with respect to starting characteristics, and because of starting difficulties considerable maintenance on manual starters is required. Additionally, as an engine becomes difiicult to start the physical energy required with a manual starter increases in order to start the engine. Women and children often use apparatus employing small internal combustion engines, and such individuals often find it impossible, or extremely difficult, to start an engine which is not in the best operating condition. Spring powered impulse starters have enjoyed some success in overcoming the aforementioned engine starting problems. However, impulse starters required a manual winding of the spring, and often are incapable of spinning the flywheel of a hard starting engine sufficiently to start the engme.

It has been long recognized that the most desirable manner of starting small internal combustion engines would be with an electric starting system and US. Pats. such as No. 2,655,047; No. 2,831,352; No. 3,070,081 and No." 3,2l9,02l show starters which have pursued this concept. Most electrically powered starters for small internal combustion engines require an electric motor supplied from house current, 110 volts AC, in order to produce the necessary torque to turn over the engine. The last three patents mentioned above are of this type, and are impractical in that the dependency upon 1 volts requires that the engine be started near an electrical outlet, a fact which negates the advantages and independence from exterior power sources of the internal combustion engine. Battery powered electric starters for small internal combustion engines such as shown by US. Pat. No. 2,655,047, have not heretofore been practical because battery powered electric motors have not heretofore been capable of producing sufficient power and torque to start the engine. By using a large enough battery to start the engine, the size, weight and cost of the battery becomes impractical, as the apparatus with which the internal combustion engine is employed is usually not large enough to readily accommodate such a battery.

The aforementioned problems in developing an electric starting system for small internal combustion engines are supported by the fact that, until the invention, no self-contained electric starting system for small engines, such as used on lawn mowers, garden equipment, and the like, has enjoyed commercial acceptance and has not been used on any significant scale. While several manufacturers of equipment using small internal combustion engines have offered electric starters which operate from 110 volts, such starters have not been commercially successful due to cost and the dependency upon an available electric outlet.

SUMMARY OF THE INVENTION The invention is directed to what is believed to be the first self-contained electric starter system for small internal combustion engines that is able to meet the practical, economical, versatility and safety requirements of this type of starter system.

' The aforementioned purposes and objects of the invention will be apparent from the following description of an embodi- 2 The invention uses a small, specially designed electric motor having an annature shaft which is disposed substantially perpendicular to the axis of thecrankshaft of the engine. A

gear housing is mounted upon the electric motor casing having a starter gear shaft perpendicularly disposed to the motor armature, and substantially radially disposed to the flywheel of the engine. A relatively small bevel gear mounted upon the motor armature shaft engages with a larger bevel gear mounted upon the starter gear shaft whereby a speed reduction and mechanical advantage is obtained between the armaj ture shaft and the starter gear shaft.

:A free end of the starter gear shaft extends from the ge housing and is provided with a spiral thread. A starter gear is mounted upon the free threaded end of this shaft having a threaded bore whichengages the spiral-thread of the shaft, arid an abutment is located at the temtinal end of the starter gear shaft to limit axial movement of the gear thereon. A compression spring is interposed between the abutment and starter which biases the starter gear away from the abutment, arid away from engagement with the engine flywheel teeth. The energization of the electric motor causes the starter gear to:axially move into engagement with the teeth of the engine flywheel, and upon the engine starting the overrunning effect disengages the starter gear from the flywheel teeth.

{The electrical power to drive the starter motor is derived from a concise battery of the rechargeable type. This battery is mounted with a case which includes an electric switch and a key lock for operating the switch. Thus, the starter cannot be energized by unauthorized persons, such as children, and inadvertent energization of the starting system is prevented. The battery case includes a connection for connecting the battery toathe engine, and also includes a recharging connection for connecting the battery to a slow rate charger.

The type of battery that is preferably used in the practice of the invention is the nickel cadmium battery, and in the commercial embodiment of the invention an engine has been started approximately two hundred times from a single charging of the battery.

One of the important advantages and objects of the invention is to produce an electric starting system which may be employed with existing engines and engine configurations, and

invention is adaptable for use with engines which are not specially designed for use with elecn-icstarters. Thus, the

gines, and does not require significant changes in engine construction. In particular, the electric starting system of the invention can easily be used on engines previously using the manual side-mounted recoil starter shown in my Application Ser. No. 519,694 now US. Pat. No. 3,375,813, since'this type of; starter requires teeth defined upon the underside of the engine flywheel.

An additional purpose of the invention is to produce an electric starter system for small internal combustion engines wherein the required gear tooth strength of the starter components could be met in a concise unit in order to insure adequate gear and tooth life.

Another object of the invention is to provide an electric starting system forsmall internal combustion engines utilizing a battery case which includes a switch and switch operating mechanism wherein these components are protected from exposure to the weather, and are not subject to damage.

BRIEF DESCRIPTION OF THE-DRAWINGS ment of the invention as illustrated in the accompanying drawings wherein:

FIG. 1 is a perspective view of a rotary lawn mower having an internal combustion engine utilizing the electric starter system of the invention;

FIG. 2 is an enlarged plan view of the small internal com 7 I .bustion engine, per se, of FIG. 1 upon which a starter in accord with the invention is mounted;

FIG. 3 is a perspective exploded view of the electric motor and starter components directly associated therewith;

FIG. 4 is an enlarged front elevational view, partly in section, of the electric starter and engine flywheel, the starter gear being shown in the retracted position in full lines, and in the flywheel engaging position in dotted lines;

FIG. 5 is a plan sectional view of the starter components as taken along Section V-V of FIG. 4, the starter gear being shown in the flywheel engaging position;

FIG. 6 is a perspective exploded view of the battery case and its components;

FIG. 7 is a perspective view of the battery case and assembled relation, illustrating the upper cover in the open position;

FIG. 8 is an elevational view of the output connector end of the battery case, when assembled; and

FIG. 9 is an elevational view of the battery case as taken from the right of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT As the startingsystem in accord with the inventive concept is intended for use with small internal combustion engines a typical utilization of the invention is shown in FIGS. 1 and 2. In FIG. 1 a lawn mover 10 is illustrated which is of therotary type and includes a frame 12 mounted upon wheels 12. A cutting blade, not shown, is disposed within the frame 14 for rotation in a horizontal plane about a vertical axis. Usually, this type of mower employs a vertical crankshaft internal combustion engine 16 similar to the type illustrated, and the blade may be directly mounted upon the lower end of the engine crankshaft. The mower includes the usual handle 18 extending upwardly from the rear of the mower, and the mower may either be manually pushed, or driven by self-propelling means connected to the engine 16.

The small internal combustion engine 10 shown in FIGS. I and 2 as used with a lawn mower may have a rated horsepower output from 1 through 6, various size engines being used with mowers of various cutting width capacities and types of drives. Such engines conventionally employ a shroud 20, which extends over the engine cylinder and flywheel 22 wherein vane structure mounted upon the flywheel will draw air through the flywheel grill 24, and push this air within the shroud over the engine cylinder wall for cooling. The upper end of the engine crankshaft is represented at 26, in FIG. 2.

Small internal combustion engines also include carburetor structure represented at 28, and a spark plug 30 threaded into a hole in the head of the cylinder. The cylinder head, not shown, is mounted upon the cylinder by bolts 32, as is the conventional practice. The engine gas tank 34 is mounted upon the engine shroud, and the crankcase oil filling cap is represented at 36.

The engine flywheel 22 is mounted on the crankshaft 26 and rotates in a horizontal plane, and includes gear teeth 38 defined upon the lower edge thereof adjacent the outer flywheel periphery, as is apparent in FIG. 4. The electric starter apparatus used with the engine is mounted on the side of the engine opposite the carburetor 28, and it is a feature of the invention that the starter mechanism closely corresponds to the configuration of the engine and does not objectionably add to the bulk of the engine, as apparent in FIG. 2, and does not extend above the vertical configuration engine, which is of an advantage in a lawn mower application where the lawn mower must have a low silhouette for mowing under bushes and the like.

The starter components that aremounted upon the engine are best illustrated in FIGS. 3 through 5. These components basically include an electric motor generally indicated at 40 which includes a cylindrical casing having a rear end enclosed by a casting 42, and a front end enclosed by a cast gear housing 44. The electric motor 40 includes an armature shaft 46 torque DC type adapted to operate on 12 volts DC, and. in the at 18 amps and 5200 r.p.m. In the commercial embodiment the motor casing is 2% inches in diameter, and 3 inches in length.

The cast gear housing 44 is mounted upon the casing front end by a pair of screws 48 which extend through the rear casting 40, motor casing and thread into housing 44 to maintain the assembly of these three components. A bearing 50 is mounted within an opening 52 defined in the gear housing 44 for rotatably supporting the motor armature shaft 46 which extends into the interior of the gear housing, and a bevel gear 54 is mounted upon the armature shaft within the gear housing. As is apparent in FIG. 3, the armature shaft 46 includes a flat 56 which cooperates with a flat portion defined in the bore 58 of the gear 54 to key the gear to the armature shaft.

A starter gear shaft 60 is rotatably mounted within the gear housing 44 and is perpendicularly disposed to the motor armature shaft 46. The shaft 60 is rotatably supported at its inner end in a bearing 62 received within a bore defined in the gear housing and the second point of support of the shaft 60 is in the gear housing cover plate 64 by means of bearing 66. Axial positioning of the shaft 60 is accomplished through a shoulder defined on the shaft engaging the wear washer 68 disposed adjacent the cover plate bearing 66. Also, a groove is defined in the shaft for receiving the snap ring 70 which will engage the inner side of the bearing 66 to complete the assembly which prevents axial movement of the starter gear shaft 60 relative to the cover plate. The cover plate 64 is removably mounted on the gear housing 44 by means of four screws 72, threadedly received within the gear housing.

The inner end of the shaft 60 is formed with a reduced diameter portion 74 for rotatable cooperation with the bearing 62, and the enlarged portion of the shafi is formed with a flat 76 which cooperates with the flat portion of the bore 78 of a large bevel gear 80. The bevel gear 80 is thus firmly keyed to the shaft 60 and rests upon a washer 82 interposed between the gear and the bearing 62.

The gears 54 and 80 may be formed by a sintered process using powdered metal, armature gear 54, in the commercial embodiment, has 12 teeth, while the large gear 80 has 23 teeth. The maximum diameter of the gear 54in the commercial embodiment is approximately 34 inches, while the diameter of the gear 80 is approximately 1% inches. Thus, it will be appreciated that a considerable mechanical advantage and speed reduction exists between these gears.

A considerable portion of the starter gear shaft extends exteriorily from the gear housing 44 to form a free unsupported end. This free end is formed with spiral threads 84 of a substantially square configuration, which are of a right hand. The terminal end 86 of the shaft is provided with an axially threaded bore 88, having threads which are of a left hand. An abutment screw 90 includes a left hand threaded stem threaded into bore 88 and an enlarged head 92 having an annular spring receiving groove 94, FIG. 5.

The starter gear 96 is mounted upon the free threaded end of the starter gear shaft 60 and includes a toothed portion 98 mounted upon a hub 100 having a cylindrical portion extending toward the abutment screw 90. The gear 96 is provided with a threaded bore 102 which meshes with the shaft threads 84 wherein relative angular rotation of the gear 96 upon the shaft 60 axially displaces the gear along the shaft threaded portion. A lightweight compression spring 104 is interposed between the enlarged head 92 of abutment screw 90, and the toothed portion 98 of the gear 96, as is apparent in FIGS. 4

and 5. The spring 104 is received within the groove 94 of the abutment screw, and a small annular groove 106 is defined in the toothed portion of the gear 96 for receiving the other end of the spring. The spring 104 is capable of rotating relative to both the abutment screw 90 and the gear 96, and tends to exert a relatively weak biasing force on the gear 96 away from the abutment screw, and also functions to produce a slight frictional resistance to rotation of the gear upon the threads commercial embodiment produces 30 inch ounces of torque 75 84.

Mounting of the electric starter assembly upon the engine 16 is accomplished through a pair of mounting brackets. The front end of the starter assembly employs a sheet metal mounting bracket 108 affixed to the gear housing 44 by screws 110 extending through holes 112. The bracket includes a portion 114 which extends downwardly along the side of the engine, FIG. 1, and is attached to the engine crankcase by a bolt 116 extending through the bracket hole 118, and threaded into a threaded hole defined in the engine whereby a relationship, as will be apparent in FIGS. 1 and 4, is produced. The rear end of the starter motor assembly is attached to the cylinder head bolts 32 by means of a right angle stamped metal bracket 120 connected to the slotted flange 122 formed upon the casting 42. Bolts 124, FIG. 2, engage threaded holes 126 formed in the bracket 120 to connect the bracket to the casting, and the engine head bolts 32 extend through the bracket holes 128.

By means of the mounting brackets 108 and 120 the starter between the gear 96 and the shaft 60 will be produced in the opposite direction to that above which will axially translate the gear toward the gear housing cover plate 64 to the full line position of FIG. 4 and completely disengage the starter gear from the engine flywheel teeth.

In the commercial embodiment of the invention the speed with which the flywheel 22 is rotated by the starter motor will quickly start most small internal combustion engines regardless of the age of the engine, and the temperature. A toothed starter gear 96 having an 8 pitch is preferably used in order to provide a high strength gear tooth which is not likely tobreak under normal operating conditions, and-by the use of the speed reduction gears 54 and 80 a very efiicient balance of mechanical characteristics is obtained between the electric motor capabilities, the torque requirements to crank the engine and the strength requirements of the gears and other starter components that will insure relatively trouble free long life.

motor assembly is mounted in a manner wherein the armature The power Source f the smer motor assembly consists f shaft 46 is substantially horizontal, and the starter gear shaft 60 extends under the periphery of the engine flywheel, FIG. 4, in a radial manner with respect to the engine flywheel, as will be apparent in FIG. 5 wherein the engine flywheel is represented by the dotted line.

As is apparent in FIG. 2, the mounting of the starter motor assembly places the assembly immediately adjacent the engine in a manner which substantially corresponds to the engine configuration, and locates the starter motor assembly below the upper portions of the engine. Thus, the starter assembly in accord with the invention does not add objectionable bulk to the engine, or provide objectionable protuberances. Also, an important advantage of the disclosed electric starter arrangement is that the electric starter apparatus can be used with many engines now on the market without modification to the engines. Merely by making minor changes in the brackets 108 and 120 a wide variety of engine models may be employed with this type of starter apparatus, and only the requirement of a flywheel having teeth defined in the lower edge thereof departs from the usual engine construction, and many internal combustion engines now on the market use side mounted recoil starters employing flywheels having gear teeth formed in the flywheel lower periphery.

When the engine is not being used, or during normal running, the starter components will be as shown in full lines in FIG. 4. The spring 104 will maintain the starter gear 96 adjacent the cover plate 64 as shown in full lines in FIG. 4, and the axial force imposed on the starter gear, as well as the resistance to rotation of the starter gear due to vibration by the spring, will keep the starter gear from accidentally engaging the teeth 38 of the flywheel.

Upon the electric motor 40 being energized the shaft 60 will be very quickly rotated. Due to the inertia of the gear 96 the initial rotation of the shaft 60 will not immediately rotate the starter gear 96 at an equal rotational speed and thus relative angular rotation will exist between the shaft threaded portion 84 and the starter gear. Because of the thread 84 this relative angular rotation will axially move the gear 96 into engagement with the teeth 38 of the flywheel 22. Engaging of the starter gear teeth 98 with the flywheel gear teeth is aided by a bevel 130, FIG. 4, formed on each of the starter gear teeth. As soon as the starter gear teeth engage the flywheel teeth rotation of the starter gear is prevented which causes the starter gear to continue its axial movement on the threaded portion 84 until the outer end surface of the gear hub 100 engages the abutment screw head 92, as shown in FIG. 5. At this time the starter gear teeth 98 will be in full engagement with the flywheel gear teeth 38 as shown in dotted lines in FIG. 4.

Engagement of the starter gear with the abutment screw 90 will firmly lock the gear 96 with respect to the shaft 60 and crank the engine flywheel until the engine starts. As soon as the engine starts the gear 96 will be overrun" and caused to rotate at a speed faster than that produced by the rotation of a rechargeable battery mounted within a two-piece battery case which includes switch and switch actuating apparatus as well as means for charging the battery and connecting the battery to the electric starting motor. The features of the battery and battery case of the starter apparatus are shown in FIGS. 6 through 9.

The battery case 132 includes a lower receptacle portion 134, and an upper receptacle portion which constitutes a cover 136 for the lower portion. Preferably, the battery case portions are formed of a synthetic plastic material which is readily molded, attractive in appearance, dielectric and noncorrodible. The lower portion 134 is provided with a joining edge 138, and the cover portion includes a joining edge 140 corresponding to the joining edge 138 whereby the portions may be firmly interconnected together in a watertight connection by means of screws I42 extending through the portion 134 and threaded into bosses 144 in the cover portion 136.

Each of the battery case portions is provided with a mounting projection 146 adjacent its joining edge, FIGS. 8 and 9. These projections each include a tapered edge 148 whereby upon assembly of the battery case portions a wedge-shaped projection is defined by the edges 148. The battery case may be mounted to a lawn mower handle, for instance, such as shown in FIG. 1, by a sheet metal bracket 150, FIG. 6, upon which a tapered recess 152 is defined by lipped flanges 154. Thus, the bracket may be slipped upon the assembled mounting projections 146 and firmly locked thereto by frictional forces. The bracket 150 may be affixed to a flat surface by bolts or by means of U-clamps 156. The battery case may be attached to a lawn mower handle or other convenient shaft or rod upon the apparatus using an engine employing a starting system of the invention.

The battery 158 located within the case portion 134 is of the rechargeable type consisting of twelve interconnected cells located in six shells. Preferably, this battery is of the nickelcaidmium type such as sold by the General Electric Company, Catalog No. 41BO0ILD04 6752 rated at 14.4 volts and 1.0 amp hours.

The batteries may be encased within an envelope of paper, plastic bubble paper, or other material, not shown, which will firmly position the batteries within the case, and protect the batteries against shock and vibration.

An electric switch 160, having an actuating button 162, is mounted to'the underside of the case cover portion 136 by rivets 164, and a key lock mechanism 166 is mounted in the cover 136 which includes a earn 168 disposed adjacent the switch actuator button 162. The return torsion spring 170 forms a part of the key lock assembly, and upon the key 172 being inserted into the key lock assembly the cam 168 may be rotated to selectively actuate the switch button 162, and close the switch 160. The return spring 170 will normally maintain the key lock in a position which removes the cam from the the shaft 60 by the electric motor. 'Ihus, angular rotation 75 switch actuator 162, whereintheswitch willbenormally open.

A power output connector 174 is mounted within the cover portion 136 and includes a pair of terminals. Likewise, a recharging connection 176 is mounted in the case portion cover and also includes a pair of terminals. The connections 174 and 176 are exteriorly accessible, and are different in characteristics in order to prevent mistakes in connecting conductors to the battery case.

A conductor 178 connects the terminal 180 of the battery to the terminal 182 of the recharging connection 176. This terminal is also connected to a terminal 184 of the output connector 174 by a conductor 186. The other battery conductor 188 is connected to the other rechargeable connector terminal 190, and this terminal is connected to the switch terminal 192 by the conductor 194. A conductor 196 connects the other switch terminal 198 to the remaining terminal 200 of the output connector.

The conductor 202, FIGS. 1 and 2, which supplies the electric motor 40 is connected to the battery case output connector 174, and in this manner an assembly such as apparent from FIG. 1 can be provided wherein the battery case 132 is conveniently located for access by the operator without stooping.

When it is desired to start the engine 16 the operator merely inserts the key 172 into the key lock 166 and rotates the key lock sufiiciently to close the switch 160. The starter motor 40 is then energized and the starter gear 96 automatically engages the flywheel gear teeth 38 and cranks the engine. Upon the engine starting the operator permits the key lock 166 to return to the off position under the influence of the spring 170 or manually turns the key lock to the off position.

Recharging of the battery 158 is readily accomplished by means of a small inexpensive trickle charger 204 as illustrated in FIG. 6. The trickle charger may be plugged into a 110 volt outlet, and by means of cord 206 the polarized connection 208 may be plugged into the polarized pin terminals of the recharging connector 176. The trickle charger 204 may be constructed in accord with US. Pat. No. 3,237,079 having an output of I ma. Thus, when the apparatus upon which the engine is mounted is stored within the garage, the trickle charger may be connected to the battery, to insure that the battery is at a full charge condition when the engine is to be started. The commercial embodiment of the invention has started a small internal combustion engine as many as two hundred times on a single charge of the battery and, thus, it will be appreciated that the starter system of the apparatus produces a practical electric starter for small internal combustion engines.

It is appreciated that various modifications to the inventive concept may be apparent to those skilled in the art without departing from the spirit of the invention, and the scope of the invention is intended to be defined only by the following claims:

I claim:

1. An electric starting system for small internal combustion engines including a flywheel having an axis of rotation and gear teeth defined thereon, comprising, in combination, an electric motor mounted upon the engine to be started, a starter gear drivingly connected to said electric motor and meshing with the flywheel gear teeth during energization of said electric motor, a battery case, a battery within said battery case, an electric switch mounted on said battery case, and conductors interconnecting said battery, switch and electric motor whereby closing said switch energizes said electric motor and rotates the engine flywheel.

2. In an electric starting system as in claim 1 wherein said battery is rechargeable, a recharging terminal connection mounted on said battery case, and conductors within said case connecting said terminal connection to said battery.

3. In an electric starting system as in claim 2, said electric motor including an armature shaft having an axis substantially perpendicularly disposed to the engine flywheel axis and said motor is mounted in close relationship to the engine to conform to the configuration thereof, and a starter gear shaft substantially radially disposed to the engine flywheel axis, said starter gear being mounted on said starter gear shaft and gear means drivingly connecting said armature shaft to said starter ture shaft, a bearing received within said opening supporting said shaft, a starter gear shaft rotatably in said housing having a free end extending from said housing, said gear shaft being substantially perpendicular to said armature shaft, a first gear fixed on said armature shaft and located within said housing, a second gear fixed on said starter gear shaft located within said housing and meshing with said first gear, spiral thread means defined on said free end of said starter gear shaft, a starter gear mounted upon said gear shaft free end having a bore circumscribing said thread means, thread means engaging means defined upon said starter gear meshing with said thread means whereby relative angular rotation between said starter gear shaft and starter gear axially translates said starter gear upon said gear shaft over said thread means, and starter gear abutment means mounted at the terminal end of said shaft free end limiting axial movement of said starter gear upon said thread means.

5. In an electric starter system as in claim 4, a compression spring circumscribing said starter gear shaft and thread means, said spring being interposed between said abutment means and said starter gear biasing said starter gear away from said abutment and permitting relative rotation between said starter gear and said starter gear shaft.

'6. In an electric starter system as in claim 5 wherein said spring rotatably engages said starter gear and said abutment.

7. In an electric starter system as in claim 4, wherein said starter gear abutment means comprises a headed screw threaded into a threaded bore defined in the terminal end of said starter gear shaft, said screw having a spiral of opposite direction with respect to the direction of spiral of said thread means.

8. In an electric starter system as in claim 4, a battery case, a rechargeable battery within said battery case, an electric switch within said battery case, a key lock mounted on said battery case adapted to actuate said switch, and electric conductors connecting said battery to said switch and said switch to said electric motor whereby closing of said switch by said key lock energizes said electric motor.

9. In an electric starting system for small internal combustion engines employing an electric engine starter motor, a battery case, a battery within said case, an electric switch mounted on said case, a switch actuator associated with said switch, a power output connection mounted on said case adapted to be electrically connected to the engine starter motor, and electric conductors connecting said battery to said switch and said switch to said output connection.

10. In an electric starting system as in claim 9, a key lock mounted on said battery case adjacent said switch actuator and means mounted on said key lock operating said actuator and switch upon operating said key lock.

11. In an electric starting system as in claim 10, said battery case consisting of first and second receptacle portions each having a joining edge, said battery being received within said first portion and said switch and key lock being mounted within said second portion, and fastening means releasably interconnecting said first and second portions maintaining said joining edges in engagement.

12. In an electric starting system as in claim 11, a mounting projection defined on each of said first and second casing receptacle portions adjacent the associated joining edge, said projections each including an edge obliquely disposed to the associated joining edge whereby upon interconnecting said casing portions said projections jointly define a mounting boss trical conductors include a first conductor connecting said battery first terminal to said recharging connection first terminal, a second conductor connecting said battery second terminal to said recharging connection second terminal, a third conductor connecting said recharging connection first terminal with said switch first terminal, a fourth conductor connecting said recharging connection second terminal with said output connection second terminal, and a fifth conductor connecting said switch second terminal with said output connection first terminal. 

